Surgical loading unit including an articulating end effector

ABSTRACT

A surgical loading unit includes an elongate body, an end effector pivotably coupled to the elongate body, and a flexible knife bar extending through a distal portion of the elongate body and a proximal portion of the end effector. Articulation of the end effector relative to the elongate body in a first direction moves a first segment of the knife bar in the first direction and moves a second segment of the knife bar in a second direction, opposite the first direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 62/500,259 filed May 2, 2017, the entiredisclosure of which is incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates generally to surgical loading units forendoscopic use and, more specifically, to surgical loading units havingarticulation assemblies for articulating an end effector of the surgicalloading unit.

Background of Related Art

Various types of surgical instruments used to endoscopically treattissue are known in the art, and are commonly used, for example, forclosure of tissue or organs in transection, resection, anastomoses, forocclusion of organs in thoracic and abdominal procedures, and forelectrosurgically fusing or sealing tissue.

One example of such a surgical instrument is a surgical staplinginstrument. Typically, surgical stapling instruments include an endeffector having an anvil assembly and a cartridge assembly forsupporting an array of surgical staples, an approximation mechanism forapproximating the cartridge and anvil assemblies, and a firing mechanismfor ejecting the surgical staples from the cartridge assembly.

During laparoscopic or endoscopic surgical procedures, access to asurgical site is achieved through a small incision or through a narrowcannula inserted through a small entrance wound in a patient. Because oflimited area available to access the surgical site, many endoscopicinstruments include mechanisms for articulating the end effector of theinstrument in relation to a body portion of the instrument to improveaccess to tissue to be treated. In addition, some end effectors have aknife blade that translates therethrough to tissue grasped by jaws ofthe end effector. During articulation of the end effector, the knifeblade experiences a bending moment and/or a shear force that may degradethe knife blade over continued articulation of the end effector.

Accordingly, it would be beneficial to provide an improved surgicalinstrument, which includes a mechanism for articulating the end effectorrelative to the body portion in a variety of orientations withoutdamaging a knife blade that moves through the end effector.

SUMMARY

In one aspect of the present disclosure, a surgical loading unit isprovided that includes an elongate body, an end effector having aproximal portion pivotably coupled to a distal portion of the elongatebody, and a knife assembly disposed within the elongate body. The knifeassembly includes an elongate guide member and a flexible knife bar. Theelongate guide member is pivotably supported in the distal portion ofthe elongate body. The knife bar is configured to move through alongitudinally-extending channel defined through the elongate guidemember. Articulation of the end effector relative to the elongate bodyin a first direction effects movement of a distal portion of theelongate guide member in a second direction, opposite the firstdirection.

In some embodiments, the elongate body may define a first longitudinalaxis and the end effector may define a second longitudinal axis. The endeffector may be configured to move relative to the elongate body from afirst position in which the second longitudinal axis is aligned with thefirst longitudinal axis to a second position in which the secondlongitudinal axis is misaligned with the first longitudinal axis. Uponthe end effector moving to the second position, a distal portion of theend effector may be disposed on a first side of a central longitudinalaxis defined by the elongate body and the distal portion of the elongateguide member of the knife assembly may be disposed on a second side ofthe central longitudinal axis defined by the elongate body.

It is contemplated that the knife bar may be more flexible than theelongate guide member such that the elongate guide member is configuredto maintain a linear shape as a segment of the knife bar that is locateddistally of the elongate guide member flexes during articulation of theend effector.

It is envisioned that the knife assembly may further include a pair ofblow-out plates extending along opposite sides of the knife bar. Thepair of blow-out plates may have a distal portion coupled to theproximal portion of the end effector. A first blow-out plate may have aproximal portion disposed between a first lateral side of the knife barand a first lateral side of the elongate guide member, and a secondblow-out plate may have a proximal portion disposed between a secondlateral side of the knife bar and a second lateral side of the elongateguide member. The proximal portion of the first blow-out plate may beconfigured to slide relative to the elongate guide member in a firstaxial direction, and the proximal portion of the second blow-out platemay be configured to slide relative to the elongate guide member in asecond axial direction in response to the end effector articulating.

In some embodiments, the proximal portion of the end effector mayinclude first and second walls that taper proximally such that the firstand second walls cooperatively define a proximally-flaring cavitythrough which both the distal portion of the knife bar and the pair ofblow-out plates extend. Each of the first and second walls may definearcuate side surfaces that are laterally spaced from one another. Thearcuate side surface of the first wall may be configured to contact thefirst blow-out plate when the end effector articulates in the firstdirection, and the arcuate side surface of the second wall may beconfigured to contact the second blow-out plate when the end effectorarticulates in the second direction.

It is contemplated that a proximal portion of the first wall may beconfigured to contact the first blow-out plate in response to anarticulation of the end effector in the first direction to move thedistal portion of the elongate guide member in the second direction. Theproximal portion of the second wall may be configured to contact thesecond blow-out plate in response to an articulation of the end effectorin the second direction to move the distal portion of the elongate guidemember in the first direction.

It is envisioned that a proximal portion of the first wall may beconfigured to move the distal portion of the elongate guide member inthe second direction in response to an articulation of the end effectorin the first direction, and a proximal portion of the second wall may beconfigured to move the distal portion of the elongate guide member inthe first direction in response to an articulation of the end effectorin the second direction.

In some embodiments, the elongate guide member may include a proximalportion pivotably coupled to the elongate body. The proximal portion ofthe elongate guide member may have a circular tab pivotably coupled tothe elongate body, such that the elongate guide member is prevented fromtranslating longitudinally relative to the elongate body.

It is contemplated that the knife assembly may further include a trackdefining a longitudinally-extending channel. The flexible knife bar mayinclude a first knife bar shaft and a second knife bar shaft coupled toand extending parallel with the first knife bar shaft. The first knifebar shaft may extend through the channel of the elongate guide member.The second knife bar shaft may extend through the channel of the track.

It is envisioned that the track and the elongate guide member may beless flexible than the knife bar, such that the track and the elongateguide member are configured to maintain a linear shape duringarticulation of the end effector relative to the elongate body.

In some embodiments, the surgical loading unit may further include asupport structure disposed between the first and second knife bar shaftsof the flexible knife bar. The support structure may include a topsurface on which the elongate guide member is supported, and a bottomsurface on which the track is supported.

In some aspects, the elongate body may include a support structure onwhich the knife assembly is supported. The support structure may have adistal portion pivotably coupled to the proximal portion of the endeffector. The support structure may have a planar top surface thatdefines a distally-flaring cavity therein. The elongate guide member maybe disposed within the distally-flaring cavity.

It is contemplated that the elongate body may include an articulationassembly for effecting articulation of the end effector. Thearticulation assembly may include an elongated drive nut extendingthrough a proximal portion of the support structure, an elongated drivescrew extending through a distal portion of the support structure andhaving a proximal portion threadingly coupled to the drive nut, and anarticulation link having a proximal portion pivotably coupled to adistal portion of the drive screw, and a distal portion pivotablycoupled to the proximal portion of the end effector. Rotation of thedrive nut may axially move the drive screw to pivot the articulationlink and, in turn, articulate the end effector.

It is envisioned that the articulation assembly may be laterally offsetfrom a central longitudinal axis defined by the elongate body.

In some embodiments, the knife bar may have a proximal portion operablycoupled to an actuator for axially moving the knife bar through theelongate body, and a distal portion that supports a knife blade forcutting tissue. The end effector may include a staple cartridge and ananvil. The staple cartridge may define a longitudinally-extendingchannel dimensioned for slidable receipt of the knife blade.

In another aspect of the present disclosure, a surgical loading unit isprovided that includes an elongate body, an end effector having aproximal portion pivotably coupled to a distal portion of the elongatebody, and a flexible knife bar extending through the distal portion ofthe elongate body and the proximal portion of the end effector.Articulation of the end effector relative to the elongate body in afirst direction may curve a first segment of the knife bar in the firstdirection and may pivot a second segment of the knife bar in a seconddirection, opposite the first direction, while the second segmentmaintains a linear shape. The second segment may be disposed proximallyof the first segment.

BRIEF DESCRIPTION OF THE DRAWINGS

Surgical loading units including embodiments of the presently disclosedarticulation mechanism are disclosed herein with reference to thedrawings, wherein:

FIG. 1A is a perspective view of a surgical stapling instrument inaccordance with the present disclosure;

FIG. 1B is a perspective view of another surgical stapling instrument inaccordance with the present disclosure, shown in a non-articulated orlinear position;

FIG. 2A is a perspective view of a distal end portion of a surgicalloading unit for use with the surgical stapling instruments of FIGS. 1Aand 1B;

FIG. 2B is a top view of the loading unit of FIG. 2A;

FIG. 2C is a first side view of the loading unit of FIG. 2A;

FIG. 2D is a second side view of the loading unit of FIG. 2A;

FIG. 3 is a perspective view, with an outer housing removed, of theloading unit of FIG. 2A illustrating an articulation mechanism and aknife assembly thereof;

FIG. 4 is an enlarged view, with the outer housing and an inner housingremoved, of the surgical loading unit of FIG. 3;

FIG. 5 is a perspective cross-sectional view, taken along line 5-5 inFIG. 4, of the loading unit illustrating the articulation mechanism;

FIG. 6A is a top view of the cross-section of FIG. 5 illustrating theloading unit in a non-articulated position, with an end effector of theloading unit axially aligned with an elongate body of the loading unit;

FIG. 6B is a top view of the cross-section of FIG. 5 illustrating theend effector of the loading unit in a first articulated positionrelative to the elongate body of the loading unit;

FIG. 6C is a top view of the cross-section of FIG. 5 illustrating theend effector of the loading unit in a second articulated positionrelative to the elongate body of the loading unit;

FIG. 7 is a perspective view, with the outer housing of the elongatebody removed, of the surgical loading unit illustrating the knifeassembly of the loading unit;

FIG. 8 is a top, perspective view, with the inner and outer housings ofthe elongate body removed, of the surgical loading unit of FIG. 7further illustrating the knife assembly;

FIG. 9 is an enlarged view of the indicated area of detail of FIG. 8;

FIG. 10 is an enlarged view of a knife bar, blow-out plates, and a knifebar track of the knife assembly of FIG. 9;

FIG. 11 is a top, perspective view, with parts removed, of the surgicalloading unit of FIG. 9 illustrating the end effector in an articulatedposition;

FIG. 12 is a side view of the surgical loading unit of FIG. 11illustrating the end effector in the articulated position;

FIG. 13A is a side view of the surgical loading unit illustrating astaple cartridge and an anvil of the end effector in an open position;and

FIG. 13B is a cross-section, taken along line 13B-13B, of the endeffector of FIG. 13A, illustrating the staple cartridge and the anvil inan approximated configuration.

DETAILED DESCRIPTION

Persons skilled in the art will understand that the loading units andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments. It isenvisioned that the elements and features illustrated or described inconnection with one exemplary embodiment may be combined with theelements and features of another without departing from the scope of thepresent disclosure. As well, one skilled in the art will appreciatefurther features and advantages of the disclosure based on the describedembodiments. Accordingly, the disclosure is not to be limited by whathas been particularly shown and described, except as indicated by theappended claims.

As used herein, the term “distal” refers to that portion of the surgicalinstrument or loading unit which is farthest from a clinician, while theterm “proximal” refers to that portion of the surgical instrument orloading unit which is closest to the clinician. In addition, as usedherein, the term clinician refers to medical staff including doctors,nurses and support personnel.

The present disclosure is directed to a knife assembly for use in anarticulating surgical loading unit or surgical instrument. The knifeassembly includes a flexible knife bar supported on either side by aknife bar guide. The knife assembly is configured such that uponarticulation of an end effector of the loading unit relative to anelongate body of the loading unit, the knife bar of the knife assemblybends in the direction of articulation while also shifting in adirection away from the direction of articulation. The knife barshifting or pivoting in a substantially opposite direction from whichthe knife bar is being bent causes the knife bar to assume a largerradius of curvature during articulation of the end effector. Bendingalong a larger radius of curvature prolongs the life of the knife bar byreducing shear forces and/or bending moments experienced by the knifebar while also providing a greater articulation angle of the endeffector.

The present disclosure further provides an articulation assembly forarticulating an end effector of a loading unit relative to an elongatebody of the loading unit. The articulation assembly includes an elongatedrive unit and an elongate drive screw operably coupled to one anotherand each being disposed toward a distal end of the elongate body, aswill described in further detail below.

Additional advantages of the presently disclosed knife assembly,articulation assembly, and surgical loading units including thepresently disclosed knife assembly and articulation assembly aredescribed below.

FIGS. 1A and 1B illustrate surgical stapling instruments for use withsurgical loading units incorporating embodiments of the presentlydisclosed articulation assembly 130 and knife assembly 160, referencedgenerally as surgical stapling instruments 10 a and 10 b. Each of thesurgical stapling instruments 10 a and 10 b can be used with the samesurgical loading unit 100. While the depicted surgical staplinginstruments 10 a, 10 b fire staples, it is contemplated that thesurgical loading unit 100 may be adapted to fire any other suitablefastener such as clips and two-part fasteners. Additionally, while thefigures depict a linear surgical stapling instrument, it is envisionedthat the presently disclosed articulation assembly and knife assemblyare suitable for use with other types of endoscopic surgical instrumentsincluding non-linear surgical stapler loading units, endoscopic forceps,graspers, dissectors, other types of surgical stapling instruments,powered vessel sealing and/or cutting devices, etc.

Generally, with reference to FIG. 1A, the surgical instrument 10 aincludes a handle assembly 12 including a movable handle 14, an adapterassembly 16 extending from the handle assembly 12, and a surgicalloading unit 100 coupled to a distal end portion of an outer tube 18 ofthe adapter assembly 16. As known in the art, the movable handle 14 isactuatable (e.g., through one or more strokes) to cause distaladvancement of a drive rod (not shown), such that the drive rod engagesa portion of a drive assembly (not shown), which forces at least aportion of the drive assembly to translate distally, thereby firingstaples from the surgical loading unit 100. Further details of howactuation of the movable handle 14 causes distal advancement of thedrive rod are explained in U.S. Pat. No. 6,953,139 to Milliman et al.,the entire contents of which are incorporated by reference herein.

Generally, with reference to FIG. 1B, the surgical instrument 10 b is amotor-driven electromechanical device that includes a handle assembly 20including a control or button 22, an adapter assembly 24 coupled to thehandle assembly 20, and the surgical loading unit 100 disposed adjacenta distal portion 32 of an outer tube 30 of the adapter assembly 24. Theadapter assembly 24 includes an outer knob housing 26 coupled to adistal end portion of the handle assembly 20, and the outer tube 30 ofthe adapter assembly 24 extends from a distal end portion of the knobhousing 26. The button 22 of the handle assembly 20 is in electricalcommunication with a motorized drive shaft (not shown), which isoperatively coupled to an articulation assembly 130 of the loading unit100 such that actuation of the actuation button 22 causes thearticulation mechanism 130 to articulate an end effector 110 of theloading unit 100, as will be described in further detail below.

A detailed description of the various components of the handle assembly20 and the adapter assembly 24 of surgical instrument 10 b may be found,for example, in U.S. patent application Ser. No. 14/550,071 (now U.S.Patent Application Publication No. 2015/0157320), the entire contents ofwhich being incorporated by reference herein.

The loading unit 100 is adapted to be attached to the outer tube 30 ofthe adapter assembly 24 of the surgical stapling instrument 10 b (or theouter tube 18 of the adapter assembly 16 of surgical stapling instrument10 a). The loading unit 100 may be configured for a single use, or maybe configured to be used more than once and includes an elongate body102 and an end effector 110 supported on a distal portion 102 b of theelongate body 102. In some embodiments, the end effector 110, includinga staple cartridge 112 and an anvil 114, may not form part of theloading unit 100, but rather, may be directly pivotably coupled to thedistal portion 32 of the outer tube 30 of the adapter assembly 24.

The elongate body 102 of the loading unit 100 defines a firstlongitudinal axis “X1” and has a proximal portion 102 a removablyreceived within the distal portion 32 of the outer tube 30 of theadapter assembly 24 of the surgical stapling instrument 10 b using,e.g., a bayonet or luer type coupling. The elongate body 102 of theloading unit 100 may include an outer housing or tube 106 (FIG. 2A) andan inner housing or tube 108 disposed within the outer housing 106. Insome embodiments, the elongate body 102 of the loading unit 100 may beintegrally connected to or monolithically formed with the outer tube 30of the adapter assembly 24 of the surgical stapling instrument 10 b.

With reference to FIGS. 2A-2D, the end effector 110 of the loading unit100 defines a second longitudinal axis “X2” that is aligned with thefirst longitudinal axis “X1” of the elongate body 102 when the endeffector 110 is in a non-articulated position (FIGS. 2A-2D and 6A), andis misaligned with the first longitudinal axis “X1” of the elongate body102 when the end effector 110 is in an articulated position (FIGS. 6Band 6C). The end effector 110 has a proximal portion 110 a pivotablycoupled to the distal portion 102 b of the elongate body 102.

In particular, with reference to FIGS. 3-6C, the distal portion 102 b ofthe elongate body 102 of the loading unit 100 includes a supportstructure or platform 116 axially fixed within the inner housing 108 ofthe elongate body 102 (FIG. 3). The support structure 116 has anelongated, planar configuration, but in some embodiments, may assume anysuitable configuration, such as tubular, cylindrical, or the like. Thesupport structure 116 of the elongate body 102 has a distally-extendingtapered extension 118. The proximal portion 110 a of the end effector110 includes a pair of flanges 113 a, 113 b extending proximallytherefrom. The tapered extension 118 of the support structure 116 isreceived in the space defined between the pair of flanges 113 a, 113 bof the end effector 110. A pivot pin 120 extends through each of thetapered extension 118 of the support structure 116 of the elongate body102 and the pair of flanges 113 a, 113 b of the end effector 110 topivotably connect the end effector 110 to the elongate body 102. In someembodiments, other pivotable connections between the end effector 110and the elongate body 102 are contemplated, such as, for example, a balland socket connection.

With continued reference to FIGS. 3-6C, loading unit 100 includes anarticulation assembly 130 that operably interconnects the end effector110 to the elongate body 102 to facilitate articulation of the endeffector 110 relative to the elongate body 102. The presently disclosedarticulation assembly 130 is most suitable for use with the poweredsurgical stapling instrument 10 b of FIG. 1B. However, it iscontemplated that the articulation assembly 130 may be modified for usewith the manually-operated surgical stapling instrument 10 a of FIG. 1A.

The articulation assembly 130 of the loading unit 100 is laterallyoffset from a central longitudinal axis “X1” defined by the elongatebody 102 and includes an elongated drive nut 132, an elongated drivescrew 134 operably coupled to the drive nut 132, and an articulationlink 136 operably coupled to the drive screw 134. The drive nut 132 andthe drive screw 134 are axially aligned with one another and eachextends parallel and laterally offset from the central longitudinal axis“X1” of the elongate body 102. The drive nut 132 extends through aproximal portion 116 a of a longitudinal side 122 of the supportstructure 116, and the drive screw 134 extends through a distal portion116 b of the longitudinal side 122 of the support structure 116. Thedrive nut 132 is rotatably supported and axially fixed in thelongitudinal side 122 of the support structure 116, and the drive screw134 is keyed to the longitudinal side 122 of the support structure 116to prevent rotation of the drive screw 134 while permitting lineartranslation of the drive screw 134 relative to the support structure116.

By positioning the drive nut 132 and the drive screw 134 of thearticulation assembly 130 adjacent the distal end of the elongate body102 of the loading unit 100 rather than the proximal end, the amount ofclearance build up that would ordinarily occur in the proximal end ofthe elongate body 102 is reduced.

The drive nut 132 of the articulation assembly 130 has a proximalportion 132 a operably coupled to the actuation button 22 (FIG. 1B) ofthe handle assembly 20, and a distal portion 132 b. The drive screw 134of the articulation assembly 130 has a proximal portion 134 a disposedwithin the distal portion 132 b of the drive nut 132 and definesexternal threading operably coupled to internal threading defined in thedrive unit 132. As such, rotation of the drive nut 132 relative to andwithin the support structure 116, in response to an actuation of thebutton 22 (FIG. 1B), effects linear translation of the drive screw 134within and relative to the support structure 116.

The articulation link 136 of the articulation assembly 130 has aproximal portion 136 a pivotably coupled to the distal portion 134 b ofthe drive screw 134, and a distal portion 136 b pivotably coupled to theproximal portion 110 a (e.g., one or both of the flanges 113 a or 113 b)of the end effector 110. The articulation link 136 may have an arcuateconfiguration, with a convex lateral side oriented toward the pivot axisof the loading unit 100 and a concave side oriented away from the pivotaxis. In some embodiments, the articulation link 136 may assume anysuitable shape, such as, for example, linear. The articulation link 136transfers the linear motion of the drive screw 134 into a pivotingmotion to articulate the end effector 110 relative to the elongate body102.

With reference to FIGS. 6A-6C, in use, rotation of the drive nut 132 ofthe articulation assembly 130 via an actuation of the button 22 (FIG.1B) linearly translates the drive screw 134 of the articulation assembly130 in one of a proximal or distal direction based on the direction ofrotation of the drive nut 132. For example, as shown in FIG. 6B, aclockwise rotation of the drive nut 132 may result in a distaltranslation of the drive screw 134 relative to the drive nut 132. As thedrive screw 134 translates in a distal direction, indicated by arrow “A”in FIG. 6B, the articulation link 136 of the articulation assembly 130pivots about the proximal portion 136 a thereof and relative to thedistal portion 134 b of the drive screw 134 in a first direction,indicated by arrow “B” in FIG. 6B, due to the end effector 110 beingaxially fixed relative to the elongate body 102. The articulation link136 also pivots about the distal portion 136 b thereof relative to theproximal portion 110 a of the end effector 110, which effectsarticulation of the end effector 110 in the direction “B.”

Similarly, as shown in FIG. 6C, counter-clockwise rotation of the drivenut 132 may result in a proximal translation of the drive screw 134relative to the drive nut 132. As the drive screw 134 translates in aproximal direction, indicated by arrow “C” in FIG. 6C, the articulationlink 136 pivots slightly about the proximal portion 136 a thereofrelative to the distal portion 134 b of the drive screw 134. Since thedistal portion 136 b of the articulation link 136 is coupled to the endeffector 110 at a location offset from the central longitudinal axis“X2” of the end effector 110, the end effector 110 articulates relativeto the elongate body 102 in a direction indicated by arrow “D” in FIG.6C.

With reference to FIGS. 2A-2D, 3, 4, and 7-12, the knife assembly 160 ofthe loading unit 100 is illustrated. As briefly mentioned above, theknife assembly 160 includes a flexible knife bar 162 that supports aknife blade 164 (FIG. 13B) at a first or distal segment 162 a thereofand bends during the above-described articulation of the end effector110 relative to the elongate body 102.

With specific reference to FIGS. 7-12, the knife bar 162 of the knifeassembly 160 has a second or intermediate segment 162 b extendingthrough the elongate body 102 of the loading unit 100, and a third orproximal segment 162 c operably coupled to a knife bar pusher 166 tocouple the knife bar 162 to the button 22 (FIG. 1B) of the handleassembly 20, or to another actuation button of the handle assembly 20,e.g., an actuation button 23. The knife blade 164 (FIG. 13B) is coupledto or monolithically formed with the distal segment 162 a of the knifebar 162. As such, an actuation of the button 23 distally translates theknife bar 162 and the associated knife blade 164 through the endeffector 110 to cut tissue grasped by the end effector 110. The knifebar 162 is bifurcated along its length to define a pair oflongitudinally-extending knife bar shafts 168 a, 168 b (FIG. 12) havingthe support structure 116 of the elongate body 102 disposedtherebetween.

The knife assembly 160 further includes an elongate guide member ortrack 170 that supports the intermediate or second segment 162 b of theknife bar 162. The track 170 is supported on a top side 117 a of thesupport structure 116 and in the inner housing 108 (FIG. 3) of theelongate body 102 of the loading unit 100. The track 170 of the knifeassembly 160 has a linear, rectangular shape and defines alongitudinally-extending channel 172 having the intermediate segment 162b of the knife bar 162 slidably supported therein. In embodiments, thetrack 170 may assume a variety of suitable shapes, such as, for example,tubular.

The track 170 includes a bottom wall 172 on which the intermediatesegment 162 b of the knife bar 162 is supported, and a pair of parallelside walls 174, 176 extending perpendicularly from the bottom wall 172.The pair of side walls 174, 176 extend along and support respectivelateral sides 178 a, 178 b of the intermediate segment 162 b of theknife bar 162 such that the track 170 at least partially surrounds theintermediate segment 162 b of the knife bar 162. The track 170 isfabricated from a material that gives the track 170 axial stiffness,such as polyamide-imide or polyether ether ketone. The track 170 has agreater stiffness (e.g., less flexibility) than the flexible knife bar162. Due to the track 170 having a greater axial stiffness than theknife bar 162, the track 170 resists bending along its length duringarticulation of the end effector 110 to maintain the linearity of theintermediate segment 162 b of the knife bar 162.

The track 170 of the knife assembly 160 is movably supported on the topside 117 a of the support structure 116 of the elongate body 102. Thetop side 117 a of the support structure 116 defines a shallow cavity 180therein. The track 170 is pivotably supported in the cavity 180 of thesupport structure 116. The cavity 180 defined in the support structure116 has a proximal portion 180 a and a distally-flaring distal portion180 b. The distal portion 180 b of the cavity 180 allows for a distalportion 170 b of the track 170 to traverse therein during articulationof the end effector 110, as will be described in detail below. Thecavity 180 of the support structure 116 and the track 170 havesubstantially similar lengths such that the track 170 is prevented fromlongitudinal translation within the cavity 180 and relative to thesupport structure 116. In some embodiments, the track 170 may have acircular tab 182 extending from the parallel side walls 174, 176 of thetrack 170 that pivotably couples to the inner housing 108 (FIG. 3) ofthe elongate body 102 to allow for rotation of the track 170 relative tothe support structure 116, but prevents longitudinal translation of thetrack 170 relative to the support structure 116.

With continued reference to FIGS. 7-12, the knife assembly 160 furtherincludes blow-out plates or supports 184, 186 that extend along thelateral sides 178 a, 178 b of the knife bar 162, respectively. Theblow-out plates 184, 186 are more flexible than the track 170 to allowbending of the plates 184, 186 during articulation of the end effector110, but are less flexible than the knife bar 162 to prevent buckling ofthe distal segment 162 a of the knife bar 162 during articulation of theend effector 110.

Each of the blow-out plates 184, 186 has a proximal portion 184 a, 186 aand a distal portion 184 b, 186 b, respectively. The proximal portion184 a of the first blow-out plate 184 is disposed between the firstlateral side 178 a of the knife bar 162 and the first side wall 174 ofthe track 170. The proximal portion 186 a of the second blow-out plate186 is disposed between the second lateral side 178 b of the knife bar162 and the second side wall 176 of the track 170. The proximal portion184 a, 186 a of each of the blow-out plates 184, 186 are slidablyreceived within the channel 172 of the track 170.

The distal portion 184 b, 186 b of each of the blow-out plates 184, 186is fixed to the proximal portion 110 a of the end effector 110. In thisway, as the end effector 110 articulates relative to the elongate body102, one of the blow-out plates 184 or 186 will be pulled in a proximaldirection and the other of the blow-out plates 184 or 186 will be pushedin a distal direction due to changes in radial distance between theblow-out plates 184, 186 during articulation of the end effector 110.During the pushing and/or pulling of the distal portions 184 b, 186 b ofthe blow-out plates 184, 186, the proximal portions 184 a, 186 a thereofslide within and relative to the channel 172 of the track 170 and theknife bar 162.

As shown in FIG. 12, the knife assembly 160 has another track 170′ thatsupports the second knife bar shaft 168 b of the knife bar 162 andanother pair of blow-out plates 184′, 186′, each of which are disposedon the bottom side 117 b of the support structure 116. Due to thesubstantial similarity of the components of the knife assembly 160disposed on the top side 117 a of the support structure 116 and thecomponents of the knife assembly 160 disposed on the bottom side 117 bof the support structure 116, the components of the knife assembly 160on the bottom side 117 b of the support structure 116 will not bedescribed.

With continued reference to FIGS. 7-12, the proximal portion 110 a ofthe end effector 110 of the loading unit 100 cooperates with the knifeassembly 160 to facilitate bending of the knife bar 162 of the knifeassembly 160 along its axis and a shifting of the knife bar 162 relativeto the support structure 116 of the elongate body 102. The proximalportion 110 a of the end effector 110 includes first and second walls188, 190 that taper in a proximal direction. The walls 188, 190 of theend effector 110 are supported on the top flange 113 a of the endeffector 110. As described above, the knife bar 162 is divided into twoshafts 168 a, 168 b, thus the proximal portion 110 a of the end effector110 may have another pair of walls (not explicitly shown) supported onthe bottom flange 113 b of the end effector 110 for interacting with thesecond knife bar shaft 168 b of the knife bar 162. The first and secondwalls 188, 190 cooperatively define a proximally-flaring cavity 192through which both the distal segment 162 a of the knife bar 162 and thedistal portion 184 b, 186 b of each of the blow-out plates 184, 186extend. The cavity 192 of the proximal portion 110 a of the end effector110 accommodates movement of the distal segment 162 a of the knife bar162 as the knife bar 162 bends with articulation of the end effector 110in either of the first or second directions.

Each of the first and second walls 188, 190 of the end effector 110defines an arcuate side surface 194, 196, respectively. The arcuate sidesurfaces 194, 196 are laterally spaced from one another across thecavity 192 of the proximal portion 110 a of the end effector 110. Insome embodiments, the side surfaces 194, 196 of the first and secondwalls 188, 190 may assume a variety of shapes. The arcuate side surface194 of the first wall 188 is oriented toward the first lateral side 178a of the knife bar 162, and the arcuate side surface 196 of the secondwall 190 is oriented toward the second lateral side 178 b of the knifebar 162. As will be described in detail below, during articulation ofthe end effector 110 relative to the elongate body 102, the arcuate sidesurfaces 194, 196 of the respective first and second walls 188, 190 ofthe end effector 110 contact the respective blow-out plates 184, 186 tobend the blow-out plates 184, 186 and the distal segment 162 a of theknife bar 162.

In operation, the end effector 110 may be articulated relative to theelongate body 102 in either the first direction, as indicated by arrow“B” in FIGS. 6B and 11, or the second direction, as indicated by arrow“D” in FIG. 6C, via the articulation assembly 130 as described above.During articulation of the end effector 110 of the loading unit 100 inthe first direction “B” relative to the elongate body 102, the distalsegment 162 a of the knife bar 162 (e.g., the segment of the knife bar162 that spans each of the distal portion 102 b of the elongate body 102and the proximal portion 110 a of the end effector 110) bends in thefirst direction “B.”

Upon the end effector 110 achieving a threshold amount of articulation,the arcuate side surface 194 of the first wall 188 of the end effector110 contacts the first blow-out plate 184 to urge the distal andintermediate segments 162 a, 162 b of the knife bar 162 in asubstantially opposite direction as the first direction “B” (e.g., thedirection indicated by arrow “D” in FIG. 11). Further articulation ofthe end effector 110 in the direction “B” results in a proximal end 193of the first wall 188 of the end effector 110 to contact the firstblow-out plate 184 to further urge the distal and intermediate segments162 a, 162 b of the knife bar 162 in a substantially opposite directionfrom the motion of articulation of the end effector 110.

Since the second or intermediate segment 162 b of the knife bar 162 isdisposed within the channel 172 of the track 170 of the knife assembly160, movement or shifting of the knife bar 162 in the direction “D” alsocauses the track 170 to move or shift in the direction “D.” Due to theproximal portion 170 a of the track 170 being axially fixed relative tothe support structure 116, and the distal portion 170 b of the track 170being free to move, the distal portion 170 b of the track 170 pivotsabout the proximal portion 170 a thereof.

While the distal segment 162 a of the knife bar 162 is curved duringarticulation of the end effector 110, the intermediate segment 162 b ofthe knife bar 162 remains linear because the intermediate segment 162 bof the knife bar 162 extends within the track 170. As the track 170 ofthe knife assembly 160 pivots in the direction “D,” the distal portion170 b of the track 170 moves toward a first side of the centrallongitudinal axis “X1” defined by the elongate body 102 and a distalportion 110 b (FIG. 2B) of the end effector 110 moves toward a secondside of the central longitudinal axis “X1” defined by the elongate body102.

As the track 170 of the knife assembly 160 pivots about the proximalportion 170 a thereof, the knife bar 162 of the knife assembly 160 bendsat a point “P” immediately proximal the proximal portion 170 a of thetrack 170 given the knife bar 162 is disposed outside of the track 170at the point “P.” While the distal segment 162 a of the knife bar 162 isbeing bent in the direction “B” during articulation of the end effector110, the knife bar 162 at the point “P” bends in the direction “D.” Inthis way, the distal and intermediate segments 162 a, 162 b of the knifebar 162 are shifting or pivoting in an opposite direction from thedirection the distal segment 162 a of the knife bar 162 is bending orcurving. By moving the distal and intermediate segments 162 a, 162 b ofthe knife bar 162 in a direction opposite from that of the bendingdirection of the distal segment 162 a of the knife bar 162, the radiusof curvature of the distal segment 162 a of the knife bar 162 isincreased. Increasing the radius of curvature of the distal segment 162a of the knife bar 162 reduces stresses on the knife bar 162 duringarticulation of the end effector 110 in the direction “B.”

Articulation of the end effector 110 of the loading unit 100 in theopposite direction (e.g., direction “D”) causes a similar phenomenon inthe knife bar 162 of the knife assembly 160, but in the oppositedirections. In particular, as the end effector 110 is articulated in thesecond direction “D,” the distal segment 162 a of the knife bar 162 isbent or curved in the second direction “D.” Upon the end effector 110achieving a threshold amount of articulation, the arcuate side surface196 of the second wall 190 of the end effector 110 contacts the secondblow-out plate 186 of the knife assembly 160 to urge the distal andintermediate segments 162 a, 162 b of the knife bar 162 in asubstantially opposite direction as the second direction “D” (e.g.,direction “B”.)

Since the intermediate segment 162 b of the knife bar 162 is disposedwithin the channel 172 of the track 170, movement or shifting of theintermediate segment 162 b of the knife bar 162 in the direction “B”also causes the track 170 to move or pivot in the direction “B.” As thetrack 170 pivots about the proximal portion 170 a thereof, the knife bar162 bends at the point “P.” The linear profile of the intermediatesegment 162 b of the knife bar 162 is maintained by the track 170 whilethe knife bar 162 at the point “P” bends in the direction “B.” In thisway, the distal segment 162 a of the knife bar 162 is being bent orcurved in an opposite direction from the direction the distal andintermediate segments 162 a, 162 b of the knife bar 162 are shifting ormoving. By moving the distal and intermediate segments 162 a, 162 b ofthe knife bar 162 in an opposite direction from that of the bendingdirection of the distal segment 162 a of the knife bar 162, the radiusof curvature of the distal segment 162 a of the knife bar 162 isincreased. Increasing the radius of curvature of the distal segment 162a of the knife bar 162 reduce stresses on the knife bar 162 duringarticulation of the end effector 110 in the direction “D.”

With reference to FIGS. 13 and 14, the staple cartridge 112 and theanvil 114 of the end effector 110 are illustrated. Each of the staplecartridge 112 and the anvil 114 define longitudinally-extending channels115 a, 115 b, respectively. A top portion of the knife blade 164 has alaterally-extending projection 164 a slidably captured within thechannel 115 b of the anvil 114, and a bottom portion of the knife blade164 has a laterally-extending projection 164 b slidably captured withinthe channel 115 a of the staple cartridge 112. The channels 115 a, 115 bsupport the knife blade 164 therein to stabilize the knife blade 164during translation of the knife blade 164 through the end effector 110.

The present disclosure also relates to methods of using the describedsurgical stapling instruments 10 a, 10 b to perform a surgical procedureand/or to articulate an end effector of a surgical stapling loadingunit. Staples may be fired from the staple cartridge of the end effectoremploying a similar mechanism disclosed in U.S. Pat. No. 6,953,139 toMilliman et al., which has been incorporated by reference herein.

Persons skilled in the art will understand that the loading units andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments. It isenvisioned that the elements and features illustrated or described inconnection with one exemplary embodiment may be combined with theelements and features of another without departing from the scope of thepresent disclosure. As well, one skilled in the art will appreciatefurther features and advantages of the disclosure based on theabove-described embodiments. Accordingly, the disclosure is not to belimited by what has been particularly shown and described, except asindicated by the appended claims.

What is claimed is:
 1. A surgical loading unit comprising: an elongatebody; an end effector having a proximal portion pivotably coupled to adistal portion of the elongate body; and a knife assembly disposedwithin the elongate body and including: an elongate guide memberpivotably supported in the distal portion of the elongate body anddefining a longitudinally-extending channel; and a flexible knife barextending through the channel of the elongate guide member, the knifebar configured to move through the channel of the elongate guide member,wherein articulation of the end effector relative to the elongate bodyin a first direction effects movement of a distal portion of theelongate guide member in a second direction, opposite the firstdirection.
 2. The surgical loading unit according to claim 1, whereinthe elongate body defines a first longitudinal axis and the end effectordefines a second longitudinal axis, the end effector being configured tomove relative to the elongate body from a first position in which thesecond longitudinal axis is aligned with the first longitudinal axis toa second position in which the second longitudinal axis is misalignedwith the first longitudinal axis.
 3. The surgical loading unit accordingto claim 2, wherein upon the end effector moving to the second position,a distal portion of the end effector is disposed on a first side of acentral longitudinal axis defined by the elongate body and the distalportion of the elongate guide member of the knife assembly is disposedon a second side of the central longitudinal axis defined by theelongate body.
 4. The surgical loading unit according to claim 1,wherein the knife bar is more flexible than the elongate guide membersuch that the elongate guide member is configured to maintain a linearshape as a segment of the knife bar that is located distally of theelongate guide member flexes during articulation of the end effector. 5.The surgical loading unit according to claim 1, wherein the knifeassembly further includes a pair of blow-out plates extending alongopposite sides of the knife bar, the pair of blow-out plates having adistal portion coupled to the proximal portion of the end effector. 6.The surgical loading unit according to claim 5, wherein a first blow-outplate of the pair of blow-out plates has a proximal portion disposedbetween a first lateral side of the knife bar and a first lateral sideof the elongate guide member, and a second blow-out plate of the pair ofblow-out plates has a proximal portion disposed between a second lateralside of the knife bar and a second lateral side of the elongate guidemember.
 7. The surgical loading unit according to claim 6, wherein inresponse to the end effector articulating, the proximal portion of thefirst blow-out plate is configured to slide relative to the elongateguide member in a first axial direction and the proximal portion of thesecond blow-out plate is configured to slide relative to the elongateguide member in a second axial direction.
 8. The surgical loading unitaccording to claim 6, wherein the proximal portion of the end effectorincludes: a first wall that tapers proximally; and a second wall thattapers proximally such that the first and second walls cooperativelydefine a proximally-flaring cavity through which both the distal portionof the knife bar and the pair of blow-out plates extend.
 9. The surgicalloading unit according to claim 8, wherein each of the first and secondwalls defines an arcuate side surface, the arcuate side surfaces beinglaterally spaced from one another.
 10. The surgical loading unitaccording to claim 9, wherein the arcuate side surface of the first wallis configured to contact the first blow-out plate when the end effectorarticulates in the first direction, and the arcuate side surface of thesecond wall is configured to contact the second blow-out plate when theend effector articulates in the second direction.
 11. The surgicalloading unit according to claim 8, wherein a proximal portion of thefirst wall is configured to contact the first blow-out plate in responseto an articulation of the end effector in the first direction to movethe distal portion of the elongate guide member in the second direction,and the proximal portion of the second wall is configured to contact thesecond blow-out plate in response to an articulation of the end effectorin the second direction to move the distal portion of the elongate guidemember in the first direction.
 12. The surgical loading unit accordingto claim 1, wherein the proximal portion of the end effector includes: afirst wall that tapers proximally; and a second wall that tapersproximally such that the first and second walls cooperatively define aproximally-flaring cavity through which a distal portion of the knifebar extends.
 13. The surgical loading unit according to claim 12,wherein a proximal portion of the first wall is configured to move thedistal portion of the elongate guide member in the second direction inresponse to an articulation of the end effector in the first direction,and a proximal portion of the second wall is configured to move thedistal portion of the elongate guide member in the first direction inresponse to an articulation of the end effector in the second direction.14. The surgical loading unit according to claim 1, wherein the elongateguide member includes a proximal portion pivotably coupled to theelongate body.
 15. The surgical loading unit according to claim 14,wherein the proximal portion of the elongate guide member has a circulartab pivotably coupled to the elongate body, such that the elongate guidemember is prevented from translating longitudinally relative to theelongate body.
 16. The surgical loading unit according to claim 1,wherein the knife assembly further includes a track defining alongitudinally-extending channel, the flexible knife bar including: afirst knife bar shaft extending through the channel of the elongateguide member; and a second knife bar shaft coupled to and extendingparallel with the first knife bar shaft, the second knife bar shaftextending through the channel of the track.
 17. The surgical loadingunit according to claim 16, wherein the track and the elongate guidemember are less flexible than the knife bar such that the track and theelongate guide member are configured to maintain a linear shape duringarticulation of the end effector relative to the elongate body.
 18. Thesurgical loading unit according to claim 17, further comprising asupport structure disposed between the first and second knife bar shaftsof the flexible knife bar, the support structure including: a topsurface on which the elongate guide member is supported; and a bottomsurface on which the track is supported.
 19. The surgical loading unitaccording to claim 1, wherein the elongate body includes a supportstructure on which the knife assembly is supported, the supportstructure having a distal portion pivotably coupled to the proximalportion of the end effector.
 20. The surgical loading unit according toclaim 19, wherein the support structure has a planar top surface thatdefines a distally-flaring cavity therein, the elongate guide memberdisposed within the distally-flaring cavity.
 21. The surgical loadingunit according to claim 19, wherein the elongate body includes anarticulation assembly for effecting articulation of the end effector,the articulation assembly including: an elongated drive nut extendingthrough a proximal portion of the support structure; an elongated drivescrew extending through a distal portion of the support structure andhaving a proximal portion threadingly coupled to the drive nut; and anarticulation link having a proximal portion pivotably coupled to adistal portion of the drive screw, and a distal portion pivotablycoupled to the proximal portion of the end effector, wherein rotation ofthe drive nut axially moves the drive screw to pivot the articulationlink and, in turn, articulate the end effector.
 22. The surgical loadingunit according to claim 20, wherein the articulation assembly islaterally offset from a central longitudinal axis defined by theelongate body.
 23. The surgical loading unit according to claim 1,wherein the knife bar has a proximal portion operably coupled to anactuator for axially moving the knife bar through the elongate body, anda distal portion that supports a knife blade for cutting tissue.
 24. Thesurgical loading unit according to claim 23, wherein the end effectorincludes a staple cartridge and an anvil, the staple cartridge defininga longitudinally-extending channel dimensioned for slidable receipt ofthe knife blade.